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  • 1
    ISSN: 0935-6304
    Keywords: Crosslinked stationary phases ; Open-tubular capillary liquid chromatography column ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Crosslinked polysiloxane stationary phases were prepared on soda-lime glass capillaries and applied to the separation of polynuclear aromatic hydrocarbons and of phthalates in reversedphase liquid chromatography. Preparation procedures and chromatographic performance of these columns are described.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0935-6304
    Keywords: Epoxytriacylglycerols ; high temperature gas chromatography ; hydroxytriacylglycerols ; ketotriacylglycerols ; lipids ; negative chemical ionization mass spectrometry ; SOP-50 ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Five seed oils consisting of unusual triacylglycerols have been examined by high temperature gas chromatography using glass capillary columns coated with the stationary phase SOP-50 (50%-diphenyl-50%-dimethylpolysiloxane, methoxy-terminated). The investigated hydroxy, epoxy, and ketokonjuene triacylglycerols were first derivatized in order to permit analysis by high temperature gas chromatography. Structural elucidation of the intact triacylglycerols was performed with high temperature gas chromatography/negative chemical ionization-mass spectrometry using NH3 as a reagent gas. Individual derivatized lipid species with a molecular weight up to 1176 g/mol could be identified.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0935-6304
    Keywords: cis-13-Eicosenoic Acid (Paullinic Acid) ; Cyanolipids ; Fatty acids ; GLC-MS ; NMR spectroscopy ; Oxazoline derivatives ; Paullinia elegans Sapindaceae ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The fatty acids of the total lipids, triglycerides, and the cyanolipid of Paullinia elegans (Sapindaceae) have been analyzed as their methyl esters and 4,4-dimethyloxazoline derivatives by gas chromatography-mass spectrometry. It was shown that the gas chromatographic separation of the oxazoline derivatives was sufficient to ensure the correct identification of the monoenic fatty acid positional isomers. Stereochemistry of the double bonds has been confirmed by infrared and 13C-nuclear magnetic resonance (NMR) spectroscopy. cis-13-Eicosenoic Acid (Paullinic acid) (44.4%) and cis-11-octadecenoic acid (cis-vaccenic acid) (19.8%) were found to be the main components beside other monoenoic acid positional isomers. The cyanolipid of P. elegans was identified as 2,4-dihydroxy-3-methylenebutyronitrile derivative by IR, 1H-NMR, 13C-NMR spectroscopy and was quantified by 1H-NMR spectroscopy (71.4%).
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0935-6304
    Keywords: α-Monoacetotriacylglycerides ; Celastraceae ; Fatty acids ; GLC ; GLC-(NCI)MS ; Maytenus seed oils ; OV-225-OH, OH-terminated ; SOP-50, methoxy-terminated ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The seed oils of three Maytenus species have been examined by high temperature GLC using SOP-50 (methoxy-terminated) and OV-225-OH (OH-terminated) glasscapillary columns. The main compounds (71-76%) could be identified as α-mono-acetotriacylglycerols by a combination of high temperature GLC-MS in negative chemical ionization mode with a CH4/N2O mixture as reactant gas and other spectroscopical methods (infrared, 1H- and 13C-nuclear magnetic resonance spectroscopy). The OV-225-OH phase demonstrated better separation properties that the SOP-50 phase for this substance class and up to eight species of α-monoacetotriacylglycerols could be separated. The content of usual triacyclglycerols was below 1%. The results of the analysis of the individual fatty acids as their methyl esters by GC and GC-MS are also presented.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0749-1581
    Keywords: Phase-editing ; Relayed responses ; 2D HMQC-TOCSY ; NMR Spectra ; Digoxin ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An NMR technique for the determination of proton vicinal couplings relayed at the carbon chemical shift is presented. With this technique, which is an extension of DEPT-HMQC-TOCSY, it is possible to generate phaseedited 2D NMR data in which the 1H—13C relayed responses differ in phase as a function of the proton multiplicity of the carbon from whose proton(s) the response originates. A simple pulse scheme is presented to allow further simplification of the spectrum by eliminating the direct 1H—13C correlations. Thus, responses arising from methines or methyls will be of opposite phase from responses originating from methylenes; direct correlations are eliminated to minimize congestion. An example is presented with the cardiac drug digoxin.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0749-1581
    Keywords: NMR ; Region-selective inverse detected long-range heteronuclear chemical shift correlation ; Shaped pulses ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: F1 region-selected variants of the HMBC experiment were compared and evaluated. In particular, a significant advantage was demonstrated for an E-BURP-2 pulse over a Gaussian 270° pulse for region-selected applications. The Gaussian 270° pulse would still, however, be the preferred pulse for use in single-resonance, on-resonance selective excitation. Data are presented from NMR spectrometers both equipped and not equipped with programmable pulse modulators (waveform generators). Pulse evaluations were performed using the simple heteroaromatic alkaloid quindoline; application of the technique to the important immunosuppressive cyclic peptide cyclosporin-A is also presented and discussed.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; XAD-2 resin ; Fungicide residues, determination in wine and grape juice ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The fungicides Bupirimate, Fenarimol, and Vinclozolin were sprayed on Vines. The fruits were harvested 8 and 21 days after the final application and processed to juice and wine. The fungicide residues were determined by filtration of the samples throug XAD-2 after pH adjustment, elution with methylene chloride, and glass capillary gas chromatography with SE-30 as stationary phase. Residue values of the three compounds were reported before and after fermentation. The precision of the analytical method was established by spiking portuguese white wine and spanish grape juice with the three fungicides and Triadimefon. The recoveries were in the range 80%-100%, except for Vinclozolin.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Polyaromatic hydrocarbons ; Airborn Particulates ; Aircraft turbines ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Whisker-walled open tubular columns ; PNA-hydrocarbons ; XAD-2 ; Azaarenes ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A modified clean-up of polynuclear aromatic (PNA) hydrocarbons on XAD-2 is described. n-Alkanes (C16—C28) are separated quantitatively from the PNA hydrocarbons and are eluted in one fraction. The distribution of 17 PNA hydrocarbons and four of their alkyl derivatives, two S-heterocyclic compounds and two azaarenes between the different fractions is reported. Azaarenes containing three rings are separated from PNA hydrocarbons and S-heterocyclic compounds. Whisker-walled open tubular columns coated with OV-215 and OV-25 were used in the separation of isomeric azaarenes and in PNA hydrocarbon profile analysis, respectively. The preparation of such columns is described in detail. Rinsing of capillary columns with cold, concentrated HCI after whisker growth removes much larger amounts of boron and sodium than subsequent leaching with HCI at 180°C. Whisker-walled open tubular columns are successfully applied to the characterization of isomeric benzofluoranthenes and other PNA hydrocarbons isolated from air particulate matter.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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